I can relate, I’m Work in Truck equipment and have to answer a lot of phone calls and be quick on my feet verbally. I’m a 80% myself, with mainly blocking and some repetition. Most days are good, but others... not so much. If I’m ever having a “off day” with my speech I like to think of it either as a game, more like a role play event where I’m imitating an accent or person. It could be either be for fun, or for intensely focusing on this call and read out like your a marine in maritime. Confidence and repetition are key IMO, I wish you luck.